October 6, 2004
Taking a form of HRT can sharply increase the risk of developing a blood clot for some women, research suggests.
Researchers found taking HRT [Premarin, Prempro, Provera] containing the hormones Estrogen and Progestin [a synthetic hormone Medroxyprogesterone Acetate, not bio-identical natural progesterone] doubled the risk of venous thrombosis for all women who took it for five years.
However, the risk was significantly higher still for older women, and those who were overweight or obese.
he research, by the University of Vermont, is published in the Journal of the American Medical Association.
The study is based on an analysis of data from 16,608 postmenopausal women between the ages of 50 and 79.
The researchers found that venous thrombosis occurred in 167 women taking combined HRT, compared with just 76 who were taking a dummy pill.
Women aged 60 to 69 were 4.3 times more likely to develop a clot if taking combined HRT, while women in their seventies were at 7.5 times the risk.
The risk of a blood clot also increased sharply for overweight and obese women taking combined HRT.
For overweight women the risk was 3.8 times higher than those of normal weight, and for obese women it was 5.6 times higher.
The researchers calculated that over a 10 year period combined HRT would be responsible for an extra 18 cases of venous thrombosis if taken by 1,000 women.
A venous thrombosis is a type of blood clot which can travel to the lungs, and potentially cause life-threatening complications.
Explain the risks
Lead researcher Dr Mary Cushman told BBC News Online that the findings were important [and] the risks and benefits [should be] fully explained before they [women patients] started on a course of treatment.
“You have to weigh all the risks of taking it, and of not taking it,” she said.
“It is thought that the hormones contained in HRT may increase the risk of a blood clot by interfering with the body’s clotting mechanism.
Combined HRT has previously been linked to an increased risk of breast cancer and stroke.
June Davison, of the British Heart Foundation, said previous research had also shown that HRT might increase the risk of venous thrombosis, but she said the new work highlighted the fact that overweight women were particularly vulnerable.
“This implies that maintaining a healthy weight by eating a balanced diet and regular physical activity is particularly important for these women.
“Anyone concerned about taking HRT should discuss it with their doctor before making any changes to their medication.”
Story from BBC NEWS:
Published: 2004/10/06 07:00:41 GMT